1. Field of the Invention
The present invention relates to a wireless power transmission system. The invention also relates to a method for designing such a system. In particular, the present invention relates to a method for designing the mutually cooperating antennas in the system by finding the optimum inductances of them based on the coupling factor.
2. Description of the Related Art
A technique called “wireless power transmission” or “wireless energy transfer” is known. With this technique, it is possible to transfer electric power from a power supply to a load in a wireless manner, i.e., without using tangible conductors such as metal wires.
The technique has been applied to power supply in cell phones, home electrical appliances or electric cars. For instance, Japanese Patent No. 4962621 discloses an application of wireless power transmission using magnetic resonance for charging the storage battery of an electric car. As another example, JP-A-8-264357 discloses a monorail-type transfer system in which a power supply line is arranged along a rail, and electric power is transmitted wirelessly from the rail to a transfer vehicle.
In designing a conventional wireless power transmission system, the geometric features (such as sizes and disposition) of a power transmitting and a power receiving antennas are generally determined in view of e.g., the usage of the system, the environment in which the system is used, and the frequency used for the power transmission. On the other hand, electrical factors such as inductance of the antennas have not been duly considered in realizing efficient power transmission.